A programmatic study designed to clarify the mechanisms of hypnosis is being carried out partly because the modality has wide therapeutic application ad partly because hypnosis provides a laboratory model for the investigation of (a) experimental psychopathology, (b) altered states of consciousness, and (c) the development of meaningful dyadic relationships. Major areas of investigation include: (1) Studies to delineate hypnosis from other related but conceptually distinct phenomena such as social compliance, contagion, and the placebo response. (2) Studies of specific hypnotic phenomena; during the past year posthypnotic amnesia has been a primary focus. (3) Studies relating the ability to enter hypnosis to an individual's ability to volitionally bring about other altered states of consciousness; in particular, we have explored the relationship to (a) sleep, and (b) alpha density. (4) Studies to validate a standard clinical measure of hypnotic responsivity.